Typically in the prior art cylindrical steel pigs or drifts sized closely in diameter to the tolerance of the inside pipe diameter were drawn through a pipe, casing or tubing (hereinafter generally referred to as pipe) by a tape to determine that the pipe was of the desired inside diameter and straightness for testing pipe sections before use in such critical applications as for oil wells, etc. Typical time to rig and test a twenty to thirty foot (about 7 to 10 meters) pipe section for example would be about two minutes.
One significant problem of the prior art is the high cost of testing because of the long time taken to rig and test a pipe section. Also, the wear of the drift and the tediousness of backing out a drift stuck in a defective pipe added significant cost. Furthermore, to test various size pipe drifts of various sizes are necessary and the weight and cost of the steel drifts provide further problems. Other problems are set forth for example in the U.S. Pat. No. 2,953,919 to E. L. Potts of Sept. 27, 1960.
Yet this simple testing technique of using the drift dimensions as a test standard is preferred over the delicate instrumentation inside the drift as for example used in U.S. Pat. No. 3,024,651 R. L. McGlasson, Mar. 13, 1962 and U.S. Pat. No. 4,170,902 W. Pallan, Oct. 16, 1979, or the introduction of fluid under pressure into the pipe as in U.S. Pat. No. 3,518,873 to J. H. Iglehart et al., July 7, 1970.
Therefore it is an object of this invention to provide improved pipe testing methods and means reducing the cost and time of pipe testing and overcoming problems of the prior art including those aforesaid.